(Alexandroff-Yosida-Hewitt decomposition, see [1]}).
Any finitely additive measure \( \mu \)  can be uniquely decomposed into the sum \( \mu = \mu _1 + \mu _2 \) , where \( \mu _1 \)  is countably additive and \( \mu _2 \)  is a purely finitely additive measure.

